<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        
/*         var num = "number";
        var result = typeof num; 
    //    console.log(num);
    document.write(result); */

    var obj = {
        a: 100,
        b: undefined,
        c: 'hello'
    }
    obj.f = "love";//增加
    delete obj.a;//删除
    obj.f = 520           //改变
    console.log(obj.f)           //查找
    console.log(obj);
    </script>
</body>
</html>